This invention relates to a control apparatus for an elevator which detects the current cage position of the elevator by means of a microcomputer. More particularly, it relates to a control apparatus for storing the current position of a cage without using a backup power source as well as a storing and holding circuit.
In control apparatuses for elevators, it is important for controlling the running of a cage to detect the current position of the cage and to store and hold the detected position. In a conventional elevator apparatus, therefore, an object which moves reducing the movement of the cage in a certain proportion is provided, and the signal of a contact which is actuated by the object is obtained as a cage position signal.
With the above construction, however, the durability is low because mechanical movable parts are included, and the device becomes large in size when the storeys of a building are high. In recent years, accordingly, a measure is taken wherein as described in the official gazette of Japanese Patent Application Laid-Open No. 56-65781 by way of example, a cage position is detected with a microcomputer, the detected cage position data is stored and held in a RAM (Random Access Memory), and the cage position data of the RAM is rewritten and held each time the cage position changes.
In addition, a measure which obtains the current position information of a cage and the position information of a service floor with a microcomputer is described in the official gazette of Japanese Patent Application Laid-Open No. 58-52169 by way of example.
Here, since the positions of service floor differ depending upon individual buildings, the position information items of service floors need to be stored for each building in advance. To this end, in the position detection apparatus disclosed in the official gazette of Japanese Patent Application Laid-Open No. 58-52169, a positional data measurement running is first carried out to store the absolute position information items of the respective service floors in a RAM. In an ordinary running mode, pulses generated in accordance with the ascent or descent of the cage are counted, and the addition or substraction between the count value and the absolute position information stored in the RAM is executed, thereby to find the current position of the cage, and the service floor and the current cage position are compared, thereby to detect a position such as slowdown initiation position.
With the control apparatus for an elevator having the above construction, however, the cage position data is stored in the RAM being a volatile memory and therefore disappears at the time of power failure, and the positional correlations between calls and the cage after the recovery of power supply become unclear, so that accurate response operations to the calls cannot be performed. This has led to the problem that an expensive backup power source, or a storing and holding circuit as disclosed in the official gazette of Japanese Patent Application Laid-Open No. 57-23565 is required in the case of employing the RAM for the storage of the cage position data.
On the other hand, there has also been proposed a method in which the positional information of service floors is stored in a ROM (Read Only Memory).
The positional information stored in the ROM can be held even when the stoppage of power supply has occured. However, the positional data items of service floors must be stored in the ROM by the use of a special tool. Moreover, these positional data items of the service floors cannot be exactly foreknown. This has been attended with such a problem that the special job of writing the positional information into the ROM is necessitated in the installation site of an elevator.